Temperature and Global Warming

Study Notes

The average temperature of the surrounding environment needs to be around 82℉ (28℃) to maintain the body's temperature without external devices.
High environmental temperatures can be dangerous to the body, causing heat cramps, exhaustion, and stroke.

One of the most immediate effects of global warming is the increase in temperatures worldwide.
The average global temperature has increased by about 1.4 degrees Fahrenheit (0.8 degrees Celsius) over the past 100 years.
2016 was the hottest year on record, with a global temperature 1.78 degrees Fahrenheit (0.99 degrees Celsius) higher than usual.

The natural warming of the Earth occurs when greenhouse gases in the atmosphere trap heat from the sun.
The greenhouse effect is important for warming the planet to a comfortable average temperature (15℃) and supporting life on Earth.
Human activities, such as burning fossil fuels for energy, are increasing the natural greenhouse effect, leading to global warming.

Thermometers measure temperature in degrees.
There are three different temperature scales: Centigrade (Celsius), Fahrenheit, and Kelvin.
The Celsius scale is commonly used for scientific works and has greater scientific significance.
The Kelvin scale is used to define the zero point (0K or -273.15℃) as the lowest possible temperature.

Liquid Thermometers:
- Mercury thermometers can measure temperatures between -30℃ and 300℃ and are used in households, laboratories, and industries.
- Alcohol thermometers can measure temperatures from -115℃ to 78.15℃ and are popular due to their non-toxicity.
Resistance Thermometers:
- Made from platinum wire, they measure temperature by changing resistance.
- Used in a wide temperature range (-270℃ to +700℃).
Thermocouples:
- Consist of thin wires of different metals, welded together at the ends to form two junctions.
- Measure temperature by generating a voltage dependent on the difference in temperature between the junctions.
- Can measure temperatures as high as 2300℃ or as low as -270℃.
Thermistors:
- Resistance thermometers whose resistance is dependent on temperature.
- Made of metallic oxides, pressed into a shape and encapsulated with an impermeable material.
- There are two types: Negative Temperature Coefficient (NTC) and Positive Temperature Coefficient (PTC).
- Typically, thermistors achieve high precision within a limited temperature range of about 50℃ around the target temperature.
Radiation Thermometers:
- Measure temperature by using electromagnetic radiation from a body.
- Not based on any change of property with temperature.